Tappet



May 10-, 1927-v WILCOX TAPPET Filed July 21, 1924 m M w Patented May 10,1927.

UNITED STATES PATENT OFFICE.

MERRILL M. \HIIJCOX OF SAGINAW,

OF SAID MERRILL WIL WILCOX PRODUCTS CORPO MICHIGAN.

A CORPORATION OF TAPPET.

Application filed July 21, 1924. Serial No. 727,338.

This invention relates to tappets and pertains more particularly tocertain unprovements in the construct1on and mode of operation oftappets made of cast iron, with 6 disk-like heads or platforms havinghardpet; also, by

ened faces to receiye the actuating cams.

impacts of valve- My present improvement has as an object to provide inthe platform a means whereby the depth of hardening of the chilledworking face is made practically uniform throughout the entire area ofthe platform.

Further objects are to increase the strength of the platform towithstand long continued percussions of the cam, and do it withoutmaterially increasing the the same means weight of the tapto provide aplatform construction that assists in more effective lubrication of thetappet stem as it shoots to and from in the bore of the tappet bracket.

With the foregoing and certain other obin view which wil jects my in thespecifications 1 appear later in vention comprises the devices describedand claimed and the equivalents thereof. In the drawings tical sectionof a chilled Fig. 1 is a central veriron tappet head made in accordancewith my invention.

Fig. 2 1s atop plan view. Fig. 3 1s a central vertical section of atappet as commonly produced heretofore,

showing faulty distribution of chill.

Fig.

4 is a fragmentary part sectional view of one end of the tappet bracketshowing the tappet in its As is clearly shown in tappet head ispreferably piece of cast metal such comprises two main parts likeplatform 1 and the stem 2.

The platform has its working face 3 made raised position.

the drawings the made of a single as cast iron and namely, thediskintegral shank or flat or substantially so and hardened by chillingin the mold.

smooth, preferably by gri Upon the back of and the platform is a reinfofor example, the raised rim 4.

tions which this reinforce of real importance, not manufacture of thetapp operation.

The working face 3 i Its face is made nding.

cast integral with rcing member, as,

The funcment performs are only during the ct, but also in its s made Iextremely 1. as indicated in Fig. 1.

Heretofore tappets made of cast iron have usually been formed as shownin Fig. 3, where the de th of chill at the rim of the platform, inicated by C, may be considerably greater than at the middle 0'. Thereason for such lack of uniformity in the depth of chill is that themass of molten metal which forms the lower part of the central stem orshank, where it joins the platform, is much greater than themass at theedge portions of the platform. Consequently the edges of the platform,being thinner and therefore losing their heat more quickly, are chilledto a greater degree. Frequently the smoothing of the face by grindingresults in removing so much of the thinner chilled part of the metal atthe center of the platform as to expose a relatively soft area in thatpart, whereas it should be extremely hard. Various expedients have beendevised to increase the depth of chill in the central area and make theentire surface uniform in that regard, none of which attempts prior tomy present invention have been entirely successful, so far as I amaware. I have found by long experimenting that a simple and inexpensivechange in the configuration of the platform itself does entirelyovercome the difficulty and makes a stronger platformto resist impactsof the cam in the direction of the arrow, Fig. 3. My new constructionalso assists in improving the lubrication of the shank 2 in its bearing5, as indicated in Fig. 4. i

I reduce the central mass of metal by eliminating the crowned back ofthe customary platform, shown in Fig. 3, and extend the shank 2 down tothe flat top of the platform 1., as shown in Fig. 1. The reinforcing rim4 or its equivalent supplies a suflicienl body of molten metal at theedge of the platform to prevent its too rapid chilling. The reduction ofthe mass of molten metal at the middle as above described, together withthe increase of the mass of molten metal around the periphery of rim 4has the effect of establishing the depth of chill at the middle area ofthe platform and beneath the rim so that throughout the entire area ofthe working faces practically uniform depth is secured.

The rim 4 also acts as an oil collector which effectively splashes theoil over the rubloinp surfaces of the tappet stem, thereby greatlyincreasing the ctfectiveness of lubrication of the stem in its bracketbearing 5.

Rim 4 also strengthens the tappet platform to resist impacts of the cam,since the rim serves as a reinforcing band or rib for the back of theplatform. It has been found in practice that as compared with previousconstructions such as in Fig. 3, the strength to resist impacts againstthe face of the platform is fully fifty per cent greater in my improvedconstruction, largely due to the more uniform depth of chill madepossible by the means herein set forth.

Having thus described my invention what I claim and desire to secure byLetters Pet ent is:

In a, tappet having a shank and a platform cast integral and having theworking face of said platform hardened by chilling, a raised reinforcingmember cast integral with the platform.

In testimony whereof, I aflix my signature.

MERRILL M. WILCOX.

